Solar heat collecting pipe

ABSTRACT

[Problem] To present a solar heat collecting pipe capable of enhancing the heat collecting efficiency by suppressing the dissipation of energy transmitted to the heat medium passing through the inside of an inner pipe. 
     [Solving Means] In the solar heat collecting pipe  1  including the inner pipe  11  for receiving sunlight collected by the light collecting mechanism  2,  and transmitting energy to the heat medium  14  passing through the inside, and the outer pipe  12  covering the outer circumference of the inner pipe  11,  a solar heat absorbing film  11   a  is applied in a portion exposed to sunlight of the inner pipe  11  of the solar heat collecting pipe  1  (the portion exposed to the reflected light of the sunlight at least on the surface of the inner pipe  11,  and a heat reflecting film 11 b  is applied in a portion not exposed to sunlight from the light collecting mechanism  2.

TECHNICAL FIELD

The present invention relates to a solar heat collecting pipe, moreparticularly to a solar heat collecting pipe having an inner pipe forreceiving sunlight collected by a light collecting mechanism, andtransmitting energy to a heat medium passing through the inside, and anouter pipe covering the outer circumference of the inner pipe forforming a heat insulating space.

BACKGROUND ART

Conventionally, a solar heat collecting pipe is proposed, which has aninner pipe for receiving sunlight collected by a trough type reflector,and transmitting energy to a heat medium passing through the inside, andan outer pipe covering the outer circumference of the inner pipe forforming a heat insulating space (see, for example, patent document 1).

Such conventional solar heat collecting pipe includes various measuresfor raising the light collecting efficiency of sunlight, and forexample, the solar heat collecting pipe of patent document 1 proposes tobe provided with a structural element for converging sunlight in theinner tube, in the outer pipe covering the outer circumference of theinner pipe transmitting energy to the heat medium passing through theinside, for forming a heat insulating space.

PRIOR ART LITERATURE Patent Document

Patent document 1: Japanese Patent Application Laid-Open No. 2004-239603

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In this manner, the conventional solar heat collecting pipe is mostlydeveloped with the attention paid to the light collecting side ofsunlight of the light collecting mechanism for enhancing the heatcollecting efficiency, and the inner pipe in which heat medium passesinside has been proposed only with ideas for enhancing the heatconverging efficiency by forming fine rough surfaces, or forming asurface reflection preventive layer or infrared ray reflection layer bycoating with extremely special multiple layers.

The present invention is devised in the light of the conventional solarheat collecting pipe, and it is hence a primary object thereof topresent a solar heat collecting pipe enhanced in heat collectingefficiency by suppressing dissipation of energy transmitted to the heatmedium passing the inside of the inner pipe.

It is other object of the present invention to present a solar heatcollecting pipe capable of supporting the solar heat collecting pipewhile absorbing the thermal expansion (linear expansion) of the innerpipe when connecting adjacent solar heat collecting pipes.

It is another object of the present invention to present a solar heatcollecting pipe capable of reducing heat transfer to the glass-madeouter pipe.

Means for Solving the Problems

To achieve the objects, the solar heat collecting pipe of the presentinvention includes an inner pipe for receiving sunlight collected by alight collecting mechanism, and transmitting energy to a heat mediumpassing through the inside, and an outer pipe covering the outercircumference of the inner pipe for forming a heat insulating space, inwhich a solar heat absorbing film is applied in a portion exposed tosunlight from the light collecting mechanism at least on the surface ofthe inner pipe, and a heat reflecting film is applied in a portion notexposed to sunlight from the light collecting mechanism.

In this case, a solar heat absorbing film may be applied to the entirecircumference of the surface of the inner pipe, and a heat reflectingfilm may be applied to a portion not exposed to sunlight from the lightcollecting mechanism, or a solar heat absorbing film may be applied to aportion exposed to sunlight from the light collecting mechanism of theinner pipe, and a heat reflecting film may be applied to a portion notexposed to sunlight from the light collecting mechanism.

The solar heat absorbing film may be composed of a chrome oxide layer.

The heat reflecting film may be composed of an aluminum foil or thinplate.

Further, mutually adjacent solar heat collecting pipes may be coupledtogether by forming threads in connection parts of the inner pipes ofthe solar heat collecting pips, and connecting in non-expanding state byconnection members having threads formed at both ends, and a supportshaft protruding in the horizontal direction from the surface of theinner pipe near the coupled position may be slidably inserted into aslit in a horizontal direction formed in a solar heat collecting pipesupport member.

The solar heat collecting pipe support member may be formed in a groovestructure having a ventilation space, for shutting out the sunlightemitted from the light collecting mechanism at an end part of the outrepipe fixed and inserted into the inner pipe.

The light collecting mechanism may be a trough type reflector having aparabolic section, and the solar heat collecting pipe support member maybe affixed to the reflector, and the reflector and the solar heatcollecting pipe may be oscillatably mounted on a platform by way of acommon oscillating shaft.

Effects of the Invention

According to the solar heat collecting pipe of the invention, a solarheat absorbing film is applied in a portion exposed to sunlight from thelight collecting mechanism at least on the surface of the inner pipe,and a heat reflecting film is applied in a portion not exposed tosunlight from the light collecting mechanism, and therefore dissipationof energy transmitted to the heat medium may be suppressed, so that theheat collecting efficiency may be enhanced.

Still more, the solar heat absorbing film may be composed of a chromeoxide film, and by a relatively inexpensive structure, it is effectiveto strength absorption of energy in the heat medium passing through theinside of the inner pipe.

In addition, the heat reflecting film may be composed of an aluminumfoil or thin plate, and by a relatively inexpensive material, it iseffective to suppress dissipation of energy transmitted to the heatmedium passing through the inside of the inner pipe.

Further, mutually adjacent solar heat collecting pipes are coupledtogether by forming threads in connection parts of the inner pipes ofthe solar heat collecting pips, and connecting in non-expanding state byconnection members having threads formed at both ends, and a supportshaft protruding in the horizontal direction from the surface of theinner pipe near the coupled position is slidably inserted into a slit ina horizontal direction formed in a solar heat collecting pipe supportmember, and therefore the mutually adjacent solar heat collecting pipesare coupled easily and firmly by connecting mutually the inner pipes ofthe solar heat collecting pipes by screwing in non-expanding state bythe connection members, and the vicinity of the coupled position can besupported while absorbing the thermal expansion (linear expansion) ofthe inner pipe by the solar heat collecting pipe support member.

Besides, the solar heat collecting pipe support member may be built in agroove structure having a ventilation space, capable of shutting outsunlight emitted from the light collecting mechanism, at the end part ofthe outer pipe affixed to the inner pipe, and therefore heat transfer tothe glass-made outer pipe may be suppressed.

The light collecting mechanism is a trough type reflector having aparabolic section, and the solar heat collecting pipe support member isaffixed to the reflector, and the reflector and the solar heatcollecting pipe are oscillatably mounted on a platform by way of acommon oscillating shaft, and therefore the reflector and the solar heatcollecting pipe are composed as an oscillating body of an integralstructure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an embodiment of a solar heat collecting device making useof a solar heat collecting pipe of the present invention, in which (a)is a front view, and (b) is a side sectional view.

FIG. 2 shows a different embodiment of a solar heat collecting devicemaking use of a solar heat collecting pipe of the present invention, inwhich (a) is a front view, (b) is a plan view, and (c) is a sidesectional view.

FIG. 3 shows an embodiment of a solar heat collecting pipe of thepresent invention, in which (a) is a schematic diagram of outline, (b1)and (b2) are schematic diagrams of a section, and (c) is an explanatorydiagram of state of use.

FIG. 4 is an explanatory diagram showing a coupling and supportingstructure of a solar heat collecting pipe.

FIG. 5 is an explanatory diagram of a solar heat collecting pipe, inwhich (a) is a front sectional view, (b) is an X-X end view of (a), and(c) is a Y-Y and Z-Z end view of (a).

PREFERRED EMBODIMENT

A preferred embodiment of a solar heat collecting pipe of the presentinvention I described below while referring to the accompanyingdrawings.

FIG. 1 shows an embodiment of a solar heat collecting device making useof a solar heat collecting pipe of the present invention.

This solar heat collecting device includes a solar heat collecting pipe1 having an inner pipe 11 for receiving sunlight collected by a troughtype reflector 2 having a parabolic section as a light collectingmechanism, and transmitting energy to a heat medium 14 passing throughthe inside, and an outer pipe 12 covering the outer circumference of theinner pipe 11 for forming a heat insulating space 13.

In this case, the solar heat collecting pipe 1 and the reflector 2 aremounted on a platform 3 so as to be capable of moving the central axisL1 of the solar heat collecting pipe 1 and the reflector 2 along thenorth-south axis, and oscillating the solar heat collecting pipe 1 andthe reflector 2 by way of a common oscillating axis 4.

In addition, a sun tracing mechanism 5 is provided for rotating theoscillating axis 4 along with the motion of the sun, so that anextension direction of a side including a bisector L2 of the solar heatcollecting pipe 1 and the reflector 2 may be always directed to thedirection of the sun.

As a result, sunlight Sb always enters the reflector 2 in parallel tothe plane including the bisector L2 of the reflector 2, and thereflected light is collected on the central axis L1 of the solar heatcollecting pipe 1 mounted on the position of the focus of the reflector2.

In this preferred embodiment, the reflector 2 is composed by joining analuminum plate material as a support member and an aluminum plate memberof high reflectivity as a mirror, and fitting them into a frame memberof aluminum extrusion formed material, but, instead, a glass mirror of aflexible thin material that can be curved may be used.

Also in this preferred embodiment, the light collecting mechanism is thetrough type reflector 2 having a parabolic section, but it may be alsorealized by a Fresnel mirror type reflector composed of a plurality oflong planar division mirrors, or a known light focusing mechanism suchas linear Fresnel lens 6 as shown in FIG. 2.

In the meantime, the solar heat collecting pipe 1 of the preferredembodiment includes, as shown in FIG. 3, the inner pipe 11 for receivingsunlight collected by the reflector 2 as light collecting mechanism, andtransmitting energy to the heat medium 14 passing through the inside,and the outer pipe 12 covering the outer circumference of the inner pipe11 for forming a heat insulating space, in which a solar heat absorbingfilm 11 a is applied in a portion exposed to sunlight from the reflector2 at least on the surface of the inner pipe 11 of the solar heatcollecting pipe 1 (the portion exposed to the reflected light of thesunlight Sb at the side of the reflector 2), and a heat reflecting film11 b is applied in a portion not exposed to sunlight from the reflector2 (the portion not exposed to the reflected light of the sunlight Sb atthe opposite side of the reflector 2).

More specifically, in the portion exposed to sunlight from the reflector2 at least on the surface of the inner pipe 11 (in the embodiment, thewhole circumference ((b1) in FIG. 1) on the surface of the inner pipe 11or the range of 180 degrees at the lower side ((b2) in FIG. 3), a chromeoxide plating layer is applied as the solar heat absorbing film 11 a.

Or the solar heat absorbing film 11 a may be formed in a limited areaexposed to the sunlight from the reflector 2.

The chrome oxide plating layer as the solar heat absorbing film 11 a maybe formed at a relatively low cost by forming chrome oxide plating onthe surface of the inner pipe 11 made of a pickled steel pipe.

The material and the forming method of the solar heat absorbing film 11a are not particularly limited, and the material includes nickel asidefrom chrome oxide, and the forming method is not limited to platingprocess, but includes spraying process, physical vapor deposition (PVD),or painting, or a black color may be applied on the surface in order toenhance absorption of solar heat, or a proper selective absorbing filmmay be applied, or other conventional method may be combined.

Further, in the portion not exposed to sunlight from the reflector 2 (inthe embodiment, the range ((b1) in FIG. 3) of 180 degrees at the upperside of the surface of the solar heat absorbing film 11 a formed on theentire circumference of the surface of the inner pipe 11 or the range((b2) in FIG. 3) of 180 degrees at the upper side of the surface of theinner pipe 11, an aluminum foil or thin plate is applied as the heatreflecting film 11 b.

Or the heat reflecting film 11 b may be formed in an entire area notexposed to sunlight from the reflector 2.

The aluminum foil or thin plate as the heat reflecting film 11 b may beformed at a relatively low cost, by adhering by way of a silicone resinor other adhesive agent.

In this case, by adhering the aluminum foil or thin plate by way of asilicone resin or other adhesive agent, in addition to the heatreflecting function, an adiabatic function of the adhesive agent may beapplied (by foaming the adhesive agent, the adiabatic function may befurther enhanced), and the energy transmitted to the heat medium 14 maybe entrapped within the inner pipe 11, and energy dissipation may besuppressed.

The material and the forming method of the heat reflecting film 11 b arenot particularly limited, and a white or silver heat-resistant adiabaticpaint having a heat reflecting function (a function capable ofentrapping the energy transmitted to the heat medium 14 within the innerpipe 11), for example, ceramic adhesive or silicone resin may be used asa binder, and micro-size hollow ceramics may be contained, orheat-resistant sheet materials made of glass wool or the like, and otherconventional materials may be also used. Or an aluminum thin plate maybe bonded physically by using any band.

The inner pipe 11 may be made of steel pipe, stainless steel pipe, andother metal pipe, and the outer pipe 12 is preferably made of Kovarglass pipe, borosilicate glass pipe, or the like.

The heat insulating space 13 usually insulates heat by forming a vacuumspace between the inner pipe 11 and the outer pipe 12.

The heat medium 14 passing inside of the inner pipe 11 is water, heatmedium oil, molten salt, or other heat medium functioning as a heatmedium when heated to a temperature of hundreds of degrees centigrade,for example, about 400° C.

The solar heat collecting pipe 1 has the solar heat absorbing film 11 aapplied in the portion exposed to sunlight from the reflector 2 as lightcollecting mechanism at least on the surface of the inner pipe 11, andthe heat reflecting film 11 b applied in the portion not exposed tosunlight from the reflector 2, and therefore by the solar heat absorbingfilm 11 a, absorption of energy in the heat medium 14 passing the insideof the inner pipe 11 is enhanced, and by the heat reflecting film 11 b,energy transmitted to the heat medium 14 can be entrapped within theinner pipe 11, and dissipation of energy can be suppressed, so that theheat collecting efficiency may be enhanced.

Hereinafter, the performance of the solar heat collecting pipe isverified specifically.

[Case 1]

-   Heating temperature of heat medium: 400° C.-   Size of reflector: width 2 m, length 5 m.-   When entire surface of inner pipe is coated with solar heat    absorbing film (chrome oxide plating layer):    -   sx (273+400)⁴=11632 W/m²    -   s (Stefan-Boltzmann constant)=5.67×10⁻⁸ W/(m²·K⁴)    -   Emissivity: e=0.6, supposing inner pipe surface area: 0.534 m²,    -   Heat radiation amount: 0.6×11632×0.534=3.73 kW (1)-   When entire surface of inner pipe is coated with solar heat    absorbing film (chrome oxide plating layer), of which half    circumference is coated with heat reflecting film (aluminum foil):    -   Supposing aluminum foil emissivity: e=0.1,    -   Heat radiation amount from portion of solar heat absorbing film        (chrome oxide plating layer): 1.86 kW.    -   Heat radiation amount from portion of heat reflecting film        (aluminum foil): 0.31 kW.    -   Overall heat radiation amount: 2.27 kW (2)-   Heat amount absorbed by solar heat collecting pipe when direct    insolation from the sun is 1 kW/m²:-   When entire surface of inner pipe is coated with solar heat    absorbing film (chrome oxide plating layer):    -   Opposite side of reflector: 10×25/1000×0.9×0.95=0.11    -   Reflector side: 10×1975/2000×0.9×0.9×0.95=7.60    -   Overall heat radiation amount: 7.71 kW (3)-   When entire surface of inner pipe is coated with solar heat    absorbing film (chrome oxide plating layer), of which half    circumference is coated with heat reflecting film (aluminum foil):    -   Opposite side of reflector: 10×25/1000×0.9×0=0    -   Reflector side: 10×1975/2000×0.9×0.9×0.95=7.60    -   Overall heat radiation amount: 7.60 kW (4)-   Heat efficiency-   When entire surface of inner pipe is coated with solar heat    absorbing film (chrome oxide plating layer):    -   (3)-(1)=3.98 kW→heat efficiency: 3.98 kW/10 kW=39.8%.-   When entire surface of inner pipe is coated with solar heat    absorbing film (chrome oxide plating layer), of which half    circumference is coated with heat reflecting film (aluminum foil):    -   (4)-(2)=5.43 kW→heat efficiency: 5.43 kW/10 kW=54.3%.

[Case 2]

-   Heating temperature of heat medium: 200° C.-   Size of reflector: width 2 m, length 5 m.-   When entire surface of inner pipe is coated with solar heat    absorbing film (chrome oxide plating layer):    -   sx (273+200)⁴=2838 W/m²    -   s (Stefan-Boltzmann constant)=5.67×10⁻⁸W/(m²·K⁴)    -   Emissivity: e=0.6, supposing inner pipe surface area: 0.534 m²,    -   Heat radiation amount: 0.6×2838×0.534=0.91 kW (5)-   When entire surface of inner pipe is coated with solar heat    absorbing film (chrome oxide plating layer), of which half    circumference is coated with heat reflecting film (aluminum foil):    -   Supposing aluminum foil emissivity: e=0.1,    -   Heat radiation amount from portion of solar heat absorbing film        (chrome oxide plating layer): 0.46 kW.    -   Heat radiation amount from portion of heat reflecting film        (aluminum foil): 0.08 kW.    -   Overall heat radiation amount: 0.54 kW (6)-   Heat amount absorbed by solar heat collecting pipe when direct    insolation from the sun is 1 kW/m²:-   When entire surface of inner pipe is coated with solar heat    absorbing film (chrome oxide plating layer):    -   Opposite side of reflector: 10×25/1000×0.9×0.95=0.11    -   Reflector side: 10×1975/2000×0.9×0.9×0.95=7.60    -   Overall heat radiation amount: 7.71 kW (7)-   When entire surface of inner pipe is coated with solar heat    absorbing film (chrome oxide plating layer), of which half    circumference is coated with heat reflecting film (aluminum foil):    -   Opposite side of reflector: 10×25/1000×0.9×0=0    -   Reflector side: 10×1975/2000×0.9×0.9×0.95=7.60    -   Overall heat radiation amount: 7.60 kW (8)-   Heat efficiency-   When entire surface of inner pipe is coated with solar heat    absorbing film (chrome oxide plating layer):    -   (7)-(5)=6.80 kW→heat efficiency: 6.80 kW/10 kW=68.0%.-   When entire surface of inner pipe is coated with solar heat    absorbing film (chrome oxide plating layer), of which half    circumference is coated with heat reflecting film (aluminum foil):    -   (8)-(6)=7.06 kW→heat efficiency: 7.06 kW/10 kW=70.6%.

Thus, as a result of verification of performance of the solar heatcollecting pipe, by applying the heat reflecting film 11 b in theportion not exposed to sunlight from the reflector 2, the energytransmitted to the heat medium 14 could be entrapped within the innerpipe 11, and dissipation of energy could be suppressed, and hence theheat collecting efficiency could be enhanced, and in particular when theheating temperature of the heat medium is higher, it has been confirmedthat the heat collecting efficiency is higher.

Further, as shown in FIG. 4 and FIG. 5, the both ends of the inner pipe11 are affixed by way of an expansion difference absorbing mechanism 25for absorbing the difference in thermal expansion (linear expansion) ofthe inner pipe 11 and the outer pipe 12, consisting of metal ring 25 aand bellows 25 b bonded to the end parts of the outer ring 12.

The adjacent solar heat collecting pipes 1 thus composed are coupledtogether by forming threads in connection parts 11 c of the inner pipes11 of the solar heat collecting pipes 1, and connecting in non-expandingstate by connection members 23 having threads formed at both ends, and asupport shaft 24 protruding in the horizontal direction from the surfaceof the inner pipe 11 near the coupled position is slidably inserted intoa slit 31 in a horizontal direction formed in solar heat collecting pipesupport members 3 a 1 to 3 a 4, 3 b 1 to 3 b 3.

In this case, at one end side or near the one end side of the slit 31, anotch 32 opening upward may be formed continuously, so that the supportshaft 24 may be inserted into the slit 31 more smoothly by way of thenotch 32.

Consequently, the adjacent solar heat collecting pipes 1 are mutuallycoupled easily and firmly, by screwing and connecting the inner pipes 11of the solar heat collecting pipes in non-expanding state by theconnection members 23, and the vicinity of the coupled position can besupported while absorbing the thermal expansion (linear expansion) ofthe inner pipes 11 by means of the solar heat collecting pipe supportmembers 3 a 1 to 3 a 4, 3 b 1 to 3 b 3.

Incidentally, the end part not coupled to the solar heat collecting pipe1 of thus coupled solar heat collecting pipes 1 is formed as a free end,and, for example, by connecting a flexible pipe 26 to the inner pipe 11of the solar heat collecting pipe 1, the thermal expansion (linearexpansion) of the inner pipes 11 can be absorbed.

In the preferred embodiment, the solar heat collecting pipe supportmembers 3 a 1 to 3 a 4, 3 b 1 to 3 b 3 are affixed to the trough typereflector 2 having a parabolic section as the light collectingmechanism, and the reflector 2 and the solar heat collecting pipe 1 areoscillatably mounted on the platform 3 by way of a common oscillatingshaft 4, so that the reflector 2 and the solar heat collecting pipe 1may be formed as an oscillating body of an integral structure.

Moreover, the solar heat collecting pipe support members 3 a 1 to 3 a 4,3 b 1 to 3 b 3 are provided with a function of supporting whileabsorbing the thermal expansion (linear expansion) of the solar heatcollecting pipe 1, more specifically, the inner pipes 11, and theexpansion difference absorbing mechanism 25 consisting of metal ring 25a and bellows 25 b bonded to the end part of the outer pipe 12 affixedto the inner pipe 11, specifically bonded to the end parts of the outerring 12 is formed in a groove structure opened upward to the ventilationspace for shutting off the sunlight exposed from the reflector 2 as thelight collecting mechanism, and releasing heat by atmosphericconvection.

As a result, through the expansion difference absorbing mechanism 25consisting of metal ring 25 a and bellows 25 b bonded to the end part ofthe outer pipe 12, heat conduction to the outer pipe may be reduced.

The solar heat collecting pipe of the invention is described herein byreferring to the preferred embodiment, but it must be noted that thepresent invention is not limited to this preferred embodiment alone, butmay be changed and modified in various structures in a scope notdeparting from the true spirit thereof.

INDUSTRIAL APPLICABILITY

The solar heat collecting pipe of the invention is characterized byenhancing the heat collecting efficiency by suppressing dissipation ofenergy transmitted to the heat medium passing in the inside of the innerpipe, and hence it may be preferably used in an application of a solarheat collecting apparatus utilizing the solar heat collecting pipe.

DESCRIPTION OF THE REFERENCE NUMERALS

-   1 Solar heat collecting pipe-   11 Inner pipe-   11 a Solar heat absorbing film-   11 b Heat reflecting film-   11 c Connection part-   12 Outer pipe-   13 Heat insulating space-   14 Heat medium-   2 Reflector (light focusing mechanism)-   6 Linear Fresnel lens (light focusing mechanism)-   24 Support shaft-   25 Expansion difference absorbing mechanism-   25 a Metal ring-   26 b Bellows-   3 a 1 to 3 a 4, 3 b 1 to 3 b 3 Solar heat collecting pipe support    member-   31 Slit-   32 Notch-   Sb Sunlight

1. A solar heat collecting pipe comprising an inner pipe for receivingsunlight collected by a light collecting mechanism, and transmittingenergy to a heat medium passing through the inside, and an outer pipecovering the outer circumference of the inner pipe for forming a heatinsulating space, wherein a solar heat absorbing film is applied in aportion exposed to sunlight from the light collecting mechanism at leaston the surface of the inner pipe, and a heat reflecting film is appliedin a portion not exposed to sunlight from the light collectingmechanism.
 2. The solar heat collecting pipe according to claim 1,wherein a solar heat absorbing film is applied to the entirecircumference of the surface of the inner pipe, and a heat reflectingfilm is applied to a portion not exposed to sunlight from the lightcollecting mechanism.
 3. The solar heat collecting pipe according toclaim 1, wherein a solar heat absorbing film is applied to a portionexposed to sunlight from the light collecting mechanism of the innerpipe, and a heat reflecting film is applied to a portion not exposed tosunlight from the light collecting mechanism.
 4. The solar heatcollecting pipe according to claim 1, wherein the solar heat absorbingfilm is composed of a chrome oxide layer.
 5. The solar heat collectingpipe according to claim 1, wherein the heat reflecting film is composedof an aluminum foil or thin plate.
 6. The solar heat collecting pipeaccording to claim 1, wherein mutually adjacent solar heat collectingpipes are coupled together by forming threads in connection parts of theinner pipes of the solar heat collecting pips, and connecting innon-expanding state by connection members having threads formed at bothends, and a support shaft protruding in the horizontal direction fromthe surface of the inner pipe near the coupled position is slidablyinserted into a slit in a horizontal direction formed in a solar heatcollecting pipe support member.
 7. The solar heat collecting pipeaccording to claim 6, wherein the solar heat collecting pipe supportmember is formed in a groove structure having a ventilation space, forshutting out the sunlight emitted from the light collecting mechanism atan end part of the outre pipe fixed and inserted into the inner pipe. 8.The solar heat collecting pipe according to claim 7, wherein the lightcollecting mechanism is a trough type reflector having a parabolicsection, and the solar heat collecting pipe support member is affixed tothe reflector, and the reflector and the solar heat collecting pipe areoscillatably mounted on a platform by way of a common oscillating shaft.9. The solar heat collecting pipe according to claim 6, wherein thelight collecting mechanism is a trough type reflector having a parabolicsection, and the solar heat collecting pipe support member is affixed tothe reflector, and the reflector and the solar heat collecting pipe areoscillatably mounted on a platform by way of a common oscillating shaft.10. The solar heat collecting pipe according to claim 4, wherein theheat reflecting film is composed of an aluminum foil or thin plate. 11.The solar heat collecting pipe according to claim 2, wherein the solarheat absorbing film is composed of a chrome oxide layer.
 12. The solarheat collecting pipe according to claim 11, wherein the heat reflectingfilm is composed of an aluminum foil or thin plate.
 13. The solar heatcollecting pipe according to claim 3, wherein the solar heat absorbingfilm is composed of a chrome oxide layer.
 14. The solar heat collectingpipe according to claim 13, wherein the heat reflecting film is composedof an aluminum foil or thin plate.
 15. The solar heat collecting pipeaccording to claim 2, wherein mutually adjacent solar heat collectingpipes are coupled together by forming threads in connection parts of theinner pipes of the solar heat collecting pips, and connecting innon-expanding state by connection members having threads formed at bothends, and a support shaft protruding in the horizontal direction fromthe surface of the inner pipe near the coupled position is slidablyinserted into a slit in a horizontal direction formed in a solar heatcollecting pipe support member.
 16. The solar heat collecting pipeaccording to claim 15, wherein the solar heat collecting pipe supportmember is formed in a groove structure having a ventilation space, forshutting out the sunlight emitted from the light collecting mechanism atan end part of the outre pipe fixed and inserted into the inner pipe.17. The solar heat collecting pipe according to claim 15, wherein thelight collecting mechanism is a trough type reflector having a parabolicsection, and the solar heat collecting pipe support member is affixed tothe reflector, and the reflector and the solar heat collecting pipe areoscillatably mounted on a platform by way of a common oscillating shaft.18. The solar heat collecting pipe according to claim 3, whereinmutually adjacent solar heat collecting pipes are coupled together byforming threads in connection parts of the inner pipes of the solar heatcollecting pips, and connecting in non-expanding state by connectionmembers having threads formed at both ends, and a support shaftprotruding in the horizontal direction from the surface of the innerpipe near the coupled position is slidably inserted into a slit in ahorizontal direction formed in a solar heat collecting pipe supportmember.
 19. The solar heat collecting pipe according to claim 4, whereinmutually adjacent solar heat collecting pipes are coupled together byforming threads in connection parts of the inner pipes of the solar heatcollecting pips, and connecting in non-expanding state by connectionmembers having threads formed at both ends, and a support shaftprotruding in the horizontal direction from the surface of the innerpipe near the coupled position is slidably inserted into a slit in ahorizontal direction formed in a solar heat collecting pipe supportmember.
 20. The solar heat collecting pipe according to claim 5, whereinmutually adjacent solar heat collecting pipes are coupled together byforming threads in connection parts of the inner pipes of the solar heatcollecting pips, and connecting in non-expanding state by connectionmembers having threads formed at both ends, and a support shaftprotruding in the horizontal direction from the surface of the innerpipe near the coupled position is slidably inserted into a slit in ahorizontal direction formed in a solar heat collecting pipe supportmember.